Mutualism is an interspecific interaction in which both partners gain a net fitness benefit. However, mutualisms are vulnerable to conflict because one partner may increase its benefits at the other’s expense (cheating). In coral reef cleaning mutualisms, cleaner fishes may cheat by feeding on client mucus rather than ectoparasites, imposing costs on clients and potentially destabilising cooperation. Here, using a standardised experimental framework, we examined cheating behaviour, measured via client jolts as a proxy, in four dedicated (relying on cleaning for sustenance) and three non-dedicated (opportunistic) cleaner fish using an interaction test with three client types (predatory, visitor and resident), and the bystander test, to evaluate potential behavioural changes in the presence of a bystander. When exposed to the same standardised social stimuli, dedicated cleaners responded differently across species, showing pronounced interspecific variation in both interaction time and client jolt frequency, whereas non-dedicated cleaners showed broadly uniform behavioural profiles with rare client jolts. Although captive interactions produced generally lower jolt rates than those typically reported in the wild, cleaner responses still differed across client types, suggesting context-dependent shifts in investment and exploitation with client identity. Bystander effects were weak overall; however, Labroides bicolor significantly reduced jolt expression when a bystander was present, suggesting that reputation-related adjustment may be species-specific. These findings highlight the capacity of cleaner species to respond differently to the same social environment, revealing species-specific behavioural strategies with potential consequences for mutualism stability and the selective pressures shaping cooperation–exploitation trade-offs.

ABSTRACT The Hong Kong Grouper (Epinephelus akaara) is a commercial fish species that suffered at least 50%–80% population declines in the past 40 years throughout its distribution range due to overexploitation. Yet, limited research on distribution and habitat utilization resulted in a lack of species‐specific management strategies. Here we aim to utilize environmental DNA (eDNA) analysis as a potential tool for species detection and to provide both shedding and decay rate for future application in persistence prediction models. We first develop a novel, species‐specific, sensitive, quantitative PCR (qPCR) assay amplifying 71 bp of the mitochondrial ND2 gene. From a mesocosm experiment, we found the decay rate (0.131 ± 0.0111/h) of E. akaara to be similar to other reported marine fish species. However, the shedding rate of E. akaara (1.94 × 104 ± 2.07 × 103 copies/h/g) is generally lower than reported values of other species, likely due to the relatively low activity and energy use from solitary and sedentary behavior of groupers. This highlights the importance of empirically determining species or taxon‐specific shedding and decay rates to inform accurate abundance estimates with modeling tools for eDNA concentrations. Out of 88 water filters collected across four sampling seasons and 11 sites in Hong Kong, six samples from four different sites showed positive amplification. No samples were measured at a concentration above limit of detection of the assay, and this rarity is consistent with current observational data. Overall, we demonstrate that eDNA with qPCR assay is a promising tool to fill in knowledge gaps of endangered species with insufficient species management and conservation across its distribution.

Class-level recognition, whereby receivers learn signaller cues and associate them with class-specific information such as familiarity, guides partner choice in mutualisms and supports community stability. Yet its molecular basis is poorly understood. In Labroides dimidiatus, class-level recognition shapes its behavioural ecology: a single individual can engage in 2,300 daily interspecific interactions, favouring rapid partner assessment and categorisation based on learned cues. To probe the molecular basis of this capacity, we coupled a familiar-unfamiliar two-choice social preference test with forebrain RNA-sequencing and H3K27ac profiling at 0, 30, and 120 min, linking behaviour, transcription, and chromatin state. Behaviourally, familiarisation reduced time spent near the familiar client. At the molecular level, transcriptomic profiles varied across time points, with early differences in genes related to synaptic release and chemosensory processes, followed by changes at 30 min in genes associated with GABAergic/homeostatic functions and, at 120 min, in genes linked to neuronal remodelling, consistent with a temporally structured molecular response. Chromatin profiling revealed broad baseline accessibility with modest between-condition differences and stronger within-condition temporal shifts, suggesting that chromatin supports, rather than drives, transcriptional change. Overall, this work provides a molecular framework for class-level recognition and suggests temporally structured molecular dynamics associated with social information processing.

The anemone-anemonefish mutualism is one of the most iconic in the marine environment. While the evolution of this mutualistic relationship has contributed to the ecological success of both partners, the underlying molecular processes that establish and maintain it remain poorly understood, particularly how anemonefish tolerate anemone venom. Here, we characterize the transcriptional dynamics in both the anemonefish Amphiprion clarkii and its host anemone Entacmaea quadricolor 48 h after association, providing a rare insight into the coordinated molecular processes in both partners that underlie symbiosis establishment. Upon acclimation with an anemone, anemonefish showed differential regulation of sensory perception and memory genes in key brain regions, indicating activation of neural pathways that may facilitate host recognition and mutualism establishment. In the fish's skin, altered expression of genes involved in neurotransmitter release, cytoskeleton organization, and venom receptor proteins points to mechanisms of resistance to anemone venom. This resistance is particularly remarkable since anemone hosting fish exhibited increased expression of genes encoding mechanoreceptors, putative venom-associated proteins, and ion channels involved in nematocyst discharge, indicating the anemone does indeed mount an active response to their mutualistic partner. By simultaneously capturing the molecular responses of both symbiotic partners, our results reveal the complex, coordinated interplay of molecular events in both species that play a pivotal role in establishing this mutualistic relationship.

ABSTRACT With anthropogenic climate change driving unprecedented ocean warming and posing a major threat to marine organisms, phenotypic plasticity mediated by epigenetic mechanisms may enable acclimation and persistence across generations. MicroRNAs (miRNAs) are epigenetic regulators that have long been associated with maladaptive stress responses across generations, yet their role in facilitating transgenerational acclimation remains unexplored. To examine miRNAs’ role in transgenerational thermal plasticity, we conducted a fully factorial split-clutch design experiment in the coral reef fish Acanthochromis polyacanthus. Parents and offspring were exposed throughout development to control (+0°C) or elevated (+1.5°C) temperatures, and offspring hepatic miRNA and mRNA were profiled. We identified 678 miRNAs in A. polyacanthus , including 226 conserved and 452 novel sequences. Direct (developmental) and parental (transgenerational) warming caused similar numbers of miRNAs to alter expression, while mRNA expression was more strongly influenced by parental effects. The two parents had distinct effects on offspring miRNA-mRNA networks, with paternal warming mainly altering offspring metabolism and stress responses, while maternal exposure predominantly influencing immunity and tissue organization. Overall, mismatched parental temperatures created trade-offs in offspring, whereas congruent (biparental) warming led to a unique, non-additive, response with fewer miRNA changes and lack of stress pathway activation. Our findings reveal that miRNAs mediate both developmental and transgenerational plasticity, highlighting the capacity of transgenerational effects to influence climate resilience, while also emphasizing the necessity of accounting for both maternal and paternal contributions when predicting species’ adaptability to ocean warming.

Ocean acidification (OA) can alter the physiological and behavioural traits of marine fishes, raising concerns about how wild species will adapt to rising pCO2. Using natural volcanic CO2 vents at White Island, New Zealand, as analogues for future OA conditions, we quantified behaviours in situ and sequenced the brain transcriptomes of four highly site-attached fish species from two vents and a nearby control site with ambient pCO2, of which two species exhibit increased population densities at the vent. We found that two species showed changes in habitat preferences, and all four species with significant changes in gene expression related to circadian rhythm, visual perception, and energy metabolism at the vents. Strikingly, three differentially expressed genes, a heat shock protein (HS90A) and two immediate early genes (IEGs: JUN and FOS), were central regulators for transcriptional changes across all species at the vents. Within the circadian entrainment pathway, expression changes in opsins may act as a trigger, while core clock genes and IEGs function as downstream effectors, suggesting that elevated pCO2 may reset the circadian clock in these fishes. Notably, the two species with increased populations at the vents exhibited distinct transcriptional responses in genes involved in calcium signalling, reproduction, intracellular pH regulation and energy metabolism. Together with convergent evolution in a calcium signalling gene and an HS90 facilitator, these molecular features may confer their reproduction advantages and ability to cope with elevated pCO2. Our study provides novel insights into the molecular mechanisms underlying fish responses to OA and highlights key pathways that may support survival and ecological success under a naturally high-CO2 world.

Foraminiferal environmental DNA (eDNA) assemblages have recently emerged as a robust and complementary proxy for relative sea level (RSL) reconstruction. However, unlike traditional morphological methods, eDNA assemblages are influenced by diverse DNA sources, including propagules and juveniles, whose effects on RSL reconstruction remain poorly understood. To assess how foraminiferal eDNA from different life stages vary in taxa composition and impact RSL reconstruction, we analyzed foraminiferal eDNA from bulk, 500-63 um and <63 um size fraction sediments from mangrove and mudflat environments in subtropical Hong Kong. The eDNA assemblages in size-fractioned sediments displayed distinct patterns from those in bulk sediment eDNA across different environments. The propagule and juvenile-derived eDNA <63 um fraction exhibited a similar community structure to bulk eDNA in mudflat environments but diverged in mangrove environments, indicating a greater contribution of propagule and juvenile eDNA to the total eDNA pool in the mudflat environment. We applied Bayesian transfer function modeling to estimate the elevation of samples using different size fractions. eDNA assemblages from the <63 um fraction systematically underpredicted elevation in mangrove environments, while elevations inferred from the 500-63 um fraction and bulk sediment eDNA were accurate. Conversely, all eDNA assemblages in the mudflat-mangrove transitional zone led to the overprediction of RSL. These findings confirm the reliability of bulk sediment eDNA for RSL reconstruction in mangrove environments, while highlighting the need for caution when reconstructing RSL in transitional zones.

Coastal ecosystems worldwide are increasingly impacted by urbanization, leading to habitat degradation, pollution, and shifts in biodiversity, which in turn affect overall ecosystem stability. Although the effects of urbanization have been well documented for many taxa, cryptobenthic fish—small, benthic-associated species with strong site fidelity and specialized diets—have been largely overlooked despite their abundance, critical ecological roles, and potential as indicators of anthropogenic disturbance. In this study, we investigate the drivers of cryptobenthic fish assemblages across a pollution gradient in Hong Kong, a highly urbanized coastal city, through a combination of collection-based and environmental DNA (eDNA) techniques. Cryptobenthic fishes' species richness is comparable to that observed in pristine reef sites, however, the community composition differed along the pollution gradient, with higher abundance in highly impacted sites dominated by species such as Tridentiger trigonocephalus and Gobiopsis macrostoma, which are positively with elevated nutrient levels. Conversely, species such as Gobiospsis arenaria and Parablennius Yatabei occur exclusively in low-nutrient environments. Nitrogen emerged as key environmental driver influencing species composition, suggesting cryptobenthic fish display species-specific tolerance to nutrients. Our findings offer new insights into how urbanization influences marine biodiversity and highlight the importance of cryptobenthic fishes as ecological indicators in human-impacted environments.

Heterospecific individual recognition, the capacity to identify and remember specific members of another species, guides partner choice in mutualisms, reduces costly misclassification, and supports community stability. Yet the molecular machinery enabling such recognition is poorly understood. The cleaner wrasse Labroides dimidiatus makes heterospecific individual recognition a central feature of its behavioural ecology, through ~ 2,300 daily interspecific interactions it has developed the ability to assess and recall partners rapidly and accurately. To probe the molecular basis of this capacity, we coupled a familiar–unfamiliar two-choice social preference test with forebrain RNA-sequencing and H3K27ac profiling at 0, 30, and 120 min, linking behaviour, transcription, and chromatin state. Behaviourally, familiarisation reduced time spent near the familiar client. At the molecular level, transcriptomes traced a phased trajectory: an immediate dampening of synaptic release and chemosensory drive, a 30-min GABAergic/homeostatic adjustment, and a 120-min consolidation marked by adhesion and dendritic spine remodelling. Chromatin profiling revealed broad baseline accessibility with only modest between-condition differences and stronger within-condition temporal shifts, indicating that chromatin supports, rather than drives, transcriptional change. Overall, this work offers a molecular framework for heterospecific recognition, linking fast circuit tuning to the subsequent stabilisation of social information.

CO2-driven acidification of freshwater ecosystems is an increasing problem that could impact aquatic life in the future. Despite their physiological tolerance to naturally fluctuating pH, freshwater fishes exhibit behavioural and neurological changes in response to acidification. To determine the molecular responses associated with these anticipated impairments for the near-future, we examined the behavioural and transcriptomic responses of zebrafish (Danio rerio) to acidification, focusing on the brain and gills, which mediate behaviour and acid-base regulation. Adult zebrafish were exposed to control (∼ 500 μatm) and elevated CO2 (∼1000 μatm) for five days and submitted to Open Field and Novel Object Approach tests, revealing a decrease in anxiety-like behaviour under elevated CO2. Acidification caused differential expression of genes involved in cytoskeletal organization, cellular transport, immunity, and the visual system in the brain, indicative of brain cell rearrangements. Conversely, there was no differential gene expression observed in the gills. However, the co-expression of genes involved in immune response and oxidoreduction, which are negatively correlated with elevated pCO2, along with a reduction in anxiety-like behaviour indicate a lower level of oxidative stress. Our findings indicate that zebrafish can perform acid-base regulation despite acidity changes predicted for the end of the century, but reveal that physiological tolerance to acidification does not confer resistance to neurological and behavioural impairments caused by rapid climate change.

Cheating in mutualisms allows species to exploit benefits without reciprocating, blurring the line between cooperation and conflict. In cleaner fish, this occurs when individuals consume client mucus instead of ectoparasites, gaining higher nutritional reward at the client’s expense. We examined cheating behaviour, measured via client jolts as a proxy, in four dedicated (relying on cleaning for sustenance) and four non-dedicated (opportunistic) cleaner fish using an interaction test with three client types (predatory, visitor and resident), and the bystander test, to evaluate potential behavioural changes in the presence of a bystander. Cheating showed a species-specific pattern, with two non-dedicated species never engaging in this behaviour. Dedicated cleaners exhibited greater variability in both the amount of time spent interacting with clients and in cheating behaviour, with some species cheating consistently regardless of client type, while others adopted more selective strategies. This was particularly evident in Labroides dimidiatus , which reduced cheating with socially valuable clients, suggesting behavioural flexibility shaped by local competition and interaction frequency. The presence of a bystander revealed no significant differences in behaviour. These findings suggest that cleaner fish adopt distinct behavioural tactics, potentially reflecting different selective pressures and degrees of flexibility in managing the trade-off between cooperation and exploitation in mutualistic interactions. ### Competing Interest Statement The authors have declared no competing interest. FCT—Fundação para a Ciência e Tecnologia, I.P., PTDC/BIA-BMA/0080/2021 Research Grants Council (RGC) of Hong Kong, 17104424

Cephalopods play a central ecological role across all oceans and depths. However, under the current climate crisis, their physiology and behaviour are impacted, and we are beginning to comprehend the effects of environmental stressors at a molecular level. Here, we study the Hawaiian bobtail squid (Euprymna scolopes), known for its specific binary symbiosis with the bioluminescent bacterium Vibrio fischeri acquired post-hatching. We aim to understand the response (i.e. developmental and molecular) of E. scolopes after embryogenetic exposure to different conditions: (i) standard conditions (control), (ii) increased CO2 (∆pH 0.4 units), (iii) warming (+3°C), or (iv) a combination of the two treatments. We observed a decrease in hatching success across all treatments relative to the control, and elevated temperature shortened the developmental time. Using transcriptomics, we identified modulation in metabolic pathways and energy production, at the expense of development under increased CO2. In addition to finding differentially expressed genes related to RNA editing, we also identified several splicing events linked to phenotypic plasticity in response to increased CO2 and temperature. The data also suggest that the initiation of the symbiosis may be negatively affected by these environmental drivers of change in the biosphere, although the animal may counter these via coping mechanisms.

Reconstructing relative sea level (RSL) is essential for understanding coastal evolution and mitigating impacts of climate change. Foraminiferal assemblages are established proxies for past sea levels, but their composition can vary seasonally and spatially, affecting the reliability of morphological reconstructions. Environmental DNA (eDNA) enables high-resolution, non-invasive monitoring of foraminiferal communities and supports high-precision RSL reconstruction. However, the spatiotemporal stability of eDNA assemblages in (sub)tropical intertidal zones—and their influence on RSL reconstruction—remains uncertain. We conducted a two-year eDNA monitoring study at three intertidal stations of varying tidal elevation in Hong Kong, sampling during both dry and wet seasons to assess variability in mangrove and mudflat environments. Mid-mangrove eDNA communities exhibited temporal and spatial stability. In contrast, eDNA assemblages in mudflat and upper-mangrove environments, particularly among monothalamous foraminifera taxa, showed pronounced seasonal shifts primarily driven by environmental changes. Despite this variability in the upper-mangrove, eDNA-based elevation estimates in mangrove consistently aligned with observed elevations (within 95% credible intervals), demonstrating reliability of RSL reconstructions in these environments. However, samples from mudflats, especially during the wet season, exhibited an overprediction bias, reflecting their heightened sensitivity to seasonal and exogenous eDNA inputs. These findings highlight the need to account for seasonal and environmental variability in eDNA-based RSL reconstruction. Stable mangroves are optimal for transfer functions, while transitional/mudflat zones require caution due to higher variability. Our study provides guidance for foraminiferal eDNA application in complex, dynamic coastal settings. ### Competing Interest Statement The authors have declared no competing interest. The Research Grants Council of Hong Kong, 27300221, 17303925

Reconstructing past relative sea level provides critical insight into mechanisms driving sea-level change and informs future projections. Foraminifera are widely used sea-level proxies, but their application is often limited by poor preservation. Here, we demonstrate that foraminiferal environmental DNA and sedimentary ancient DNA provide a complementary approach to traditional morphological methods for relative sea-level reconstruction. By analyzing surface sediments and a core from subtropical intertidal environments in the Pearl River Delta, we found a clear vertical zonation in the environmental DNA assemblage consistent with morphological results. An environmental DNA-based transfer function enabled reconstruction with decadal temporal and decimeter vertical resolution for two periods: 290–1703 CE and 1956–present. Notably, sedimentary DNA preservation extended the reconstruction beyond morphological methods, which was limited by taphonomic processes. The environmental DNA reconstruction closely matched tide-gauge and geological records, underscoring its potential as a robust tool for reconstructing past relative sea level and its driving mechanisms. Foraminiferal environmental and sedimentary ancient DNAs provide a complementary approach to traditional morphological methods for relative sea level reconstruction, according to analysis of sediments in the Pearl River Delta.

Alternative splicing is a fundamental mechanism of gene expression regulation that increases mRNA diversity and can be partially regulated by the circadian clock. Time-dependent production of transcript isoforms from the same gene facilitates coordination of biological processes with the time of day and is a crucial mechanism enabling organisms to cope with environmental changes. In this study, we determined the impact of future ocean acidification conditions on circadian splicing patterns in the brain of fish, while accounting for diel CO2 fluctuations that naturally occur on coral reefs. The temporal splicing pattern observed across a 24-hour period in fish from the control group was largely absent in those exposed to either stable or fluctuating elevated CO2 conditions. Splicing patterns were influenced not only by an overall increase in CO2 concentration but also by its stability, with 6am and 6pm emerging as key timepoints when the majority of aberrant splicing events were identified. We found that fish in fluctuating CO2 conditions exhibited increased temporal plasticity in splicing events compared to fish in stable CO2 conditions. This was especially notable for genes associated with neural functioning. Our findings suggest that natural temporal splicing patterns in fish brains are disrupted by elevated CO2 exposure, with CO2 stability also influencing molecular responses. The increased plasticity in temporal splicing activity observed in fish in fluctuating CO2 environments may provide greater flexibility in biological responses to external pH changes, potentially enabling them to better cope with future ocean acidification conditions.

Open net pen saltwater aquaculture faces criticism due to the potential transmission of pathogens between fish farms and to wild stocks. To address this issue and improve the sustainability and growth of net pen farming, closed containment farms have been suggested, but the cost and feasibility of disinfecting large volumes of water in these types of farms is problematic. We explored the potential for using electrolysis to disinfect saltwater in a flow-through system with water flow velocities between 47 and 105 cm/s. This was the first step to investigating whether this technology could be applied to saltwater flow-through closed containment systems. Various voltage levels (3.3-9.0 V) were applied to generate chlorine from saltwater. We found the disinfection properties of the system varied with wattage (i.e., voltage x ampere), velocity of water flow over the electrodes, salinity of water, and residual chlorine contact time. Wattage was highly correlated with the production of chlorine, and this relationship was dependent on water flow (p = 0.0398). A slower flow velocity led to higher chlorine concentration, and the effect was more pronounced at higher wattages. Using a zero-inflated negative binomial regression model, we found the probability of full disinfection was increased by increasing wattage (p < 0.001) and the residual chlorine contact time (p < 0.001). The level of disinfection (count model) suggested the number of bacteria in the treated samples was determined by the interaction between wattage and flow (p = 0.0056) and the interaction between wattage and salinity (p < 0.001). The bacterial count was also associated with residual chlorine contact time (p < 0.001). The results of this study, although preliminary and limited in their scale, offering a potential solution for disinfecting large volumes of seawater, which could make closed containment fish farming in the ocean viable for reducing bacterial transmission within a farm and to wild fish stocks.

With temperature being a crucial factor affecting the physiology of ectothermic animals, global warming will likely impact neural mechanisms aquatic organisms use to perceive their environment over generations. However, exposure to elevated temperature during specific life stages and across generations may confer fish resilience through phenotypic plasticity. In this study, we investigate the effects of developmental and parental temperature on brain activity response to an olfactory cue in the larval zebrafish, Danio rerio . We exposed parents during reproduction and their offspring during development to control (28°C) or elevated temperature (30°C) and observed the response of the larval telencephalon to an alarm cue using live calcium imaging. Parental exposure to elevated temperature decreased the time till maximum brain activity response regardless of the offspring’s developmental temperature, revealing that parental thermal conditions can affect the excitability of the offspring’s neural circuitry. Furthermore, brain activity duration was affected by the interaction between parental and offspring thermal conditions, tending to last longer when either parents or offspring were exposed to elevated temperature, yet more similar to control when elevated temperature was experienced by both parents and offspring. This could represent an anticipatory parental effect influencing the offspring’s brain response to match the parental environment, or an early developmental effect occurring within a susceptible short time window post-fertilization. Overall, our results suggest that future predicted warming can alter processes involved in brain transmission and show that parental conditions could aid in the preparation of their offspring to respond to olfactory stimuli in a changing environment. ### Competing Interest Statement The authors have declared no competing interest.

Population and species persistence in a rapidly warming world will be determined by an organism’s ability to acclimate to warmer conditions, especially across generations. There is potential for transgenerational acclimation but the importance of ontogenetic timing in the transmission of environmentally induced parental effects remains mostly unknown. We aimed to disentangle the effects of two critical ontogenetic stages (juvenile development and reproduction) to the new-generation acclimation potential, by exposing the spiny chromis damselfish Acanthochromis polyacanthus to simulated ocean warming across two generations. By using hepatic transcriptomics, we discovered that the post-hatching developmental environment of the offspring themselves had little effect on their acclimation potential at 2.5 months of life. Instead, the developmental experience of parents increased regulatory RNA production and protein synthesis, which could improve the offspring’s response to warming. Conversely, parental reproduction and offspring embryogenesis in warmer water elicited stress response mechanisms in the offspring, with suppression of translation and mitochondrial respiration. Mismatches between parental developmental and reproductive temperatures deeply affected offspring gene expression profiles, and detrimental effects were evident when warming occurred both during parents’ development and reproduction. This study reveals that the previous generation’s developmental temperature contributes substantially to thermal acclimation potential during early life; however, exposure at reproduction as well as prolonged heat stress will likely have adverse effects on the species’ persistence.

ABSTRACTComprehensive assessments of coastal biodiversity in complex coral communities are crucial but challenging, particularly under unfavorable conditions such as poor underwater visibility in urbanized and eutrophic environments. Here we aim to examine the scope of underwater diversity detection and community shifts across habitat transitions spanning different geographic regions in Hong Kong SAR, a highly urbanized coastal city with limited underwater visibility of 3.93 ± 1.25 m during the sampling period. We employ and compare two methods: 12S rRNA eDNA metabarcoding coupled with custom built reference database and simultaneous extensive underwater visual census (UVC) surveys. eDNA detected a higher species richness per site. Yet, each survey method featured a distinct species profile with associated trophic guilds, where 98 (32.3%) species found exclusively by UVC and 120 (39.6%) species detected only by eDNA. eDNA featured species from diverse habitats and evolutionary distances, including cryptic and large mobile fishes, offering enhanced prediction on local ecosystem functions. eDNA also recorded 90 putative species that had never been recorded in additional seven yearlong UVC dataset, with seven prospective new occurrence records to the territorial waters. UVC on the other hand was more efficient in documenting reef‐associated species. Both methods captured similar patterns of community spatial structure along the habitat transitions while only eDNA detected more large fish species in offshore compared to sheltered inshore environments, This may suggest inshore overfishing and incapability of UVC in surveying large mobile species in turbid environments. Considering the discrepancies between two methods, we highlight the importance of complementing both UVC and eDNA metabarcoding survey for a complete overview of local biodiversity under unfavored underwater conditions in an urbanized seascape.